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Research Paper Hypotheses
This is a space where we can post some propose hypotheses and bounce ideas off one another. 1) Oxygen monitoring feedback mechanism in HydA gene expression We know that under aerobic conditions, not only is the activity of the HydA enzyme diminished, but that its production is also slowed/halted. What is the feedback mechanism responsible for this gene expression regulation? 2) Detaching HydA protein from the photosynthesis energy system and implanting it elsewhere in the cell The HydA enzyme requires two things to produce hydrogen gas: A source of protons and a source of electrons. In the photosynthesis system, the electron flow is cut off in the presence of oxygen. Can we plug the HydA enzyme into a different system which is not shut down in this fashion? 3) A novel method for In Vitro hydrogen production by HydA enzyme If the HydA enzyme requires protons and electrons to produce free hydrogen gas, then I propose an experiment. Combining a sample of HydA enzyme, protons in the form of a mild acid solution, and a beta-radiation source, could hydrogen gas production be accomplished outside of the cell? (Beta-radiation is blocked by several layers of aluminum foil, reducing personal health risks to a low level with the proper precautions). 4) Mutation. Can we play with Chlamy cells providing different amounts of extra electrons (beta-radiation?). Working with survived cells, maybe we can generate cells tolerant to excess of electrons. 5) PROBLEM: Presence of oxygen prevents hydrogenase production of hydrogen. Removal of all oxygen initially encourages production of hydrogen by hydrogenase but is sustainable for a limited period of time. IDEA: Cycle aerobic/anaerobic conditions to determine if it is possible for sustainable production of hydrogen by hydrogenase in either Chlamydomonas or **Scenedesmus. Paul Weaver demonstrated *“the reversibility of this hydrogenase toward O2 inactivation” with an enzyme suspension of Rubrivivax gelatinosus hydrogenase. ***3) Green algae are applicable in another method of hydrogen production. The work of Gaffron and Rubin (3) demonstrated that Scenedesmus produced hydrogen gas not only under light conditions, but also produced it fermentatively under dark anaerobic conditions, with intracellular starch as a reducing source. Although the rate of fermentative hydrogen production per unit of dry cell weight, was less than that obtained through light-dependent hydrogen production, hydrogen production was sustainable due to the absence of oxygen. Paul Weaver http://aem.asm.org/cgi/content/abstract/68/6/2633 (Using Rubrivivax gelatinosus) When either whole-cell or membrane-free partially purified hydrogenase was stirred in full air (21% O2, 79% N2), its H2 evolution activity exhibited a half-life of 20 or 6 h, respectively, as determined by an anaerobic assay using reduced methyl viologen. When the partially purified hydrogenase was stirred in an atmosphere containing either 3.3 or 13% O2 for 15 min and evaluated by a hydrogen-deuterium (H-D) exchange assay, nearly 80 or 60% of its isotopic exchange rate was retained, respectively. When this enzyme suspension was subsequently returned to an anaerobic atmosphere, more than 90% of the H-D exchange activity was recovered, reflecting the *reversibility of this hydrogenase toward O2 inactivation. Kolandaiswamy Francis and Horst Senger http://pcp.oxfordjournals.org/cgi/content/abstract/26/6/1195 **Scenedesmus cells reach full hydrogen activity after 2.5 h of anaerobic adaptation. Exposure to oxygen inactivates the hydrogenase immediately. Readaptation occurs with the same kinetics as primary adaptation. The fast activation and reactivation as well as the insensibility to cycloheximide suggest that hydrogenase, inactive or activated, is present in the chloroplast all the time. ***Hydrogen production: Link for entire article with diagrams: http://www.fao.org/docrep/W7241E/w7241e0g.htm --C. White 22:41, September 6, 2009 (UTC)